The present invention provides a new, improved and useful expendable electrode for electro-cardiographic measurements.
Expendable electrodes for electrocardiographic measurements have been known in the art. The previously known and available expendable electrodes of said applicability can be divided in two main groups, i.e. wet and dry electrodes operating, respectively, with and without a contact gel.
Wet expandable electrodes are supplied to the market without the contact gel and must be provided with a selected gel prior to being used, i.e. before their clamping or taping onto the skin. The contact gel is needed for bridging over the extremely high resistance of the epidermal corner layer of the skin. Applying the gel is a time-consuming operation and the duration depends on the selection of the gel and on the skill of the operator. To avoid the drawbacks connected with the known wet expendable electrodes, recently attempts have been made to provide them with an appropriate gel already placed thereupon. These electrodes however prove to have the drawback that the gel usually dries too quickly, so that in spite of the existing layer of gel, they must be, notwithstanding, provided with fresh gel layer. Besides, expendable electrodes of this construction are extremely expensive.
To avoid the above drawbacks and insufficiencies, dry expendable electrodes have been suggested. These comprise an integrated "FET" amplifier. The latter is an electrode having such a high impedance that the resistance of the epidermal corner layer is negligible. This, however, makes this electrode so expensive that it can be used only in very special cases where the cost does not play any considerable role.
A more recent attempt at providing an improved electrode is seen, for example, in U.S. Pat. No. 3,505,993, wherein metallic pins are provided in an attempt to enable the electrode to adhere more closely to the skin. The electrode however is rigid and must be made to conform to particular body shapes. Therefore a plurality of such units are necessary for any one operation.